--- zzzz-none-000/linux-3.10.107/arch/m68k/atari/stdma.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/m68k/atari/stdma.c	2021-02-04 17:41:59.000000000 +0000
@@ -59,6 +59,31 @@
 /************************* End of Prototypes **************************/
 
 
+/**
+ * stdma_try_lock - attempt to acquire ST DMA interrupt "lock"
+ * @handler: interrupt handler to use after acquisition
+ *
+ * Returns !0 if lock was acquired; otherwise 0.
+ */
+
+int stdma_try_lock(irq_handler_t handler, void *data)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	if (stdma_locked) {
+		local_irq_restore(flags);
+		return 0;
+	}
+
+	stdma_locked   = 1;
+	stdma_isr      = handler;
+	stdma_isr_data = data;
+	local_irq_restore(flags);
+	return 1;
+}
+EXPORT_SYMBOL(stdma_try_lock);
+
 
 /*
  * Function: void stdma_lock( isrfunc isr, void *data )
@@ -78,19 +103,10 @@
 
 void stdma_lock(irq_handler_t handler, void *data)
 {
-	unsigned long flags;
-
-	local_irq_save(flags);		/* protect lock */
-
 	/* Since the DMA is used for file system purposes, we
 	 have to sleep uninterruptible (there may be locked
 	 buffers) */
-	wait_event(stdma_wait, !stdma_locked);
-
-	stdma_locked   = 1;
-	stdma_isr      = handler;
-	stdma_isr_data = data;
-	local_irq_restore(flags);
+	wait_event(stdma_wait, stdma_try_lock(handler, data));
 }
 EXPORT_SYMBOL(stdma_lock);
 
@@ -122,22 +138,25 @@
 EXPORT_SYMBOL(stdma_release);
 
 
-/*
- * Function: int stdma_others_waiting( void )
- *
- * Purpose: Check if someone waits for the ST-DMA lock.
- *
- * Inputs: none
- *
- * Returns: 0 if no one is waiting, != 0 otherwise
+/**
+ * stdma_is_locked_by - allow lock holder to check whether it needs to release.
+ * @handler: interrupt handler previously used to acquire lock.
  *
+ * Returns !0 if locked for the given handler; 0 otherwise.
  */
 
-int stdma_others_waiting(void)
+int stdma_is_locked_by(irq_handler_t handler)
 {
-	return waitqueue_active(&stdma_wait);
+	unsigned long flags;
+	int result;
+
+	local_irq_save(flags);
+	result = stdma_locked && (stdma_isr == handler);
+	local_irq_restore(flags);
+
+	return result;
 }
-EXPORT_SYMBOL(stdma_others_waiting);
+EXPORT_SYMBOL(stdma_is_locked_by);
 
 
 /*
@@ -179,7 +198,7 @@
 void __init stdma_init(void)
 {
 	stdma_isr = NULL;
-	if (request_irq(IRQ_MFP_FDC, stdma_int, IRQ_TYPE_SLOW | IRQF_SHARED,
+	if (request_irq(IRQ_MFP_FDC, stdma_int, IRQF_SHARED,
 			"ST-DMA floppy,ACSI,IDE,Falcon-SCSI", stdma_int))
 		pr_err("Couldn't register ST-DMA interrupt\n");
 }